FreeBSD is a free Unix-like operating system much like Linux. The main difference is that, while the Linux kernel has been written from scratch, FreeBSD is based on the freely redistributable parts of 4.4BSD (Berkeley Software Distribution) known as 4.4BSD-lite. This fact might lead some people to suggest that FreeBSD is closer to being ``real'' UNIX® than Linux. FreeBSD runs only on the Intel PC platform (i386 and higher); ports to the DEC Alpha and Sun Sparc platforms are being worked on at the moment. NetBSD and OpenBSD are similar to FreeBSD, and both run on several platforms. Hardware requirements for all these *BSD systems are similar to those for Linux.

The development of FreeBSD is managed in a different way than the Linux development. A core team of developers serve as arbitrators and provide leadership for the project. Big changes are discussed in advance on the mailing lists. The FreeBSD project has two development trees (just like Linux): ``-CURRENT'' and ``-STABLE''. The ``-CURRENT'' development tree is where the development of new features happens. Development to the ``-STABLE'' tree are restricted to bug fixes and some thoroughly tested new features.

FreeBSD can be used and (re-)distributed freely just as Linux. Most parts of the system are released under the BSD copyright; the rest is under the GNU GPL or other open-source licences.